The instant invention relates to the suspension structure for seats of the type installed in truck tractors. More particularly, the instant design for a vehicle seat mounting structure provides a cushioned, double-link mechanism having a geometry which maintains a truck seat in an orientation relative to a roadway, while a truck-tractor cab containing the mounting structure oscillates in response to irregularities in the roadway.
The driver's seat in the cab of a truck-tractor, of the heavy construction type used for long-haul or heavy duty trucking, must provide proper support and comfort to it's occupant, who is frequently "in-the-seat" for up to ten hours per day. Roadway-produced motions inflicted on a driver, by the tractor cab on the roadway, can lead to serious back problems for long-haul drivers, particularly when the driver operates a cab-over-type tractor.
The cab of a truck tractor moves on its suspension with a pitching motion in a circular arc centered between the front and rear axles of the tractor. The arc is typically located at a position midway between the axles. The pitching motion is transmitted to the driver's seat through a mounting structure which secures the seat to the vehicle cab. As a truck tractor travels over the highway, the pitching motion about the circular arc tends to rock the cab forward and rearward about the axis, which, depending on vehicle load, is generally rearward of and below the driver's seat. In a cab-over, the driver's seat is typically attached to the cab directly over, or perhaps slightly rearward, of the front wheels. The driver's seat in these vehicles is generally spring or shock mounted to cushion the driver's ride as much as possible. However, the rocking action of the cab, combined with the geometry of a conventional seat mounting structure produces the "back-slap" phenomena, alternately separating the seat back from the driver's back and then subsequently forcing the seat back into the driver's back. The cab over produces some peculiar movements due to the relationship of the driver's seat, the engine and the front wheels of the tractor.
Although a number of seat geometries have been disclosed which purport to reduce back-slap, none eliminate the circular pitching motion of the driver's seat which must be eliminated to prevent the back-slap condition and the back pain which results therefrom.
A general object of the invention is to provide a mechanism in a truck seat mounting structure which eliminates the problem of back-slap which occurs in truck-tractors.
Another object of the invention is to provide a seat mounting structure with a circular arcing anti-backslap geometry.
A further object of the instant invention is to provide a truck seat mounting structure which will provide the occupant of a tractor cab with a fixed position relative to a road surface, regardless of tractor cab oscillations.
Another object of the instant invention is to provide a truck seat mounting structure which is adjustable for seat height and seat tilt.
Still another object of the invention is to provide a truck seat mounting which includes a pneumatic cushion mechanism to adjust the seat height and seat tilt through adjustment of an air-spring-suspension-shock-absorbing mechanism.
Another object of the invention is to provide a seat mounting structure which is retrofittable into existing vehicles.
A further object of the invention is to provide a seat mounting which is relatively inexpensive and simple to manufacture.